With the development of display technology, a touch type display device appears which integrates an input terminal and an output terminal, and with the appearance of a series of products such as a small and light handheld touch device, the demand for the touch type display device increases sharply in the market. In existing touch type display devices, a projection type capacitive touch device has became a main touch device because it can achieve a true multi-point touch and has an advantage of high sensitivity.
FIG. 1 shows a planar perspective view of an array substrate of a mutual inductance type capacitive touch display device among existing projection type capacitive touch devices, as shown in FIG. 1, the array substrate comprises a plurality of gate lines 11, a plurality of data lines 12, and the gate lines 11 are crossed with the data lines 12 to define a plurality of pixel units arranged in a matrix form, wherein each pixel unit is provided with a pixel electrode 13 and a thin film transistor (TFT) 14, the array substrate of the mutual inductance type capacitive touch display device further comprises a strip-shaped common electrode 15 and a sensing line 16 crossed with each other, the sensing line 16 and the data lines 12 are provided in the same layer. The common electrode 15 is time-division driven, and when a touch position is detected, an alternating current voltage is applied to the common electrode, and thus, a coupling capacitance is formed between the common electrode 15 and the sensing line 16. When a finger touches a display screen of a capacitive type display device, a new capacitance is generated between the finger and the common electrode 15 and the sensing line 16, and a position of a touch point can be determined by scanning a capacitance change at a crossing position of the common electrode 15 and the sensing line 16.
For the array substrate in the above touch display device, a sensing line is newly added in the array substrate which is provided in the same layer with the data line, which will cause a lowered aperture ratio of the display device. Further, to achieve the sensitivity of the touch displaying, the sensing line needs to be provided wide enough so as to form a coupling capacitance large enough between it and the common electrode, which further lowers the aperture ratio of the display device.